妄想姉妹 ～文學という名のもとに～

The story centers around three sisters living together, though they have very different personalities, leading them to believe they have different mothers. One day, they each receive a letter from their dead father, with each indicating the title of an erotic novel. Believing that the letters are hints about their mothers, they begin reading the books, and before they know it, they start imagining themselves as the novels' heroines.